ASTM E1181-02(2023)
(Test Method)Standard Test Methods for Characterizing Duplex Grain Sizes
Standard Test Methods for Characterizing Duplex Grain Sizes
SIGNIFICANCE AND USE
5.1 Duplex grain size may occur in some metals and alloys as a result of their thermomechanical processing history. For comparison of mechanical properties with metallurgical features, or for specification purposes, it may be important to be able to characterize grain size in such materials. Assigning an average grain size value to a duplex grain size specimen does not adequately characterize the appearance of that specimen, and may even misrepresent its appearance. For example, averaging two distinctly different grain sizes may result in reporting a size that does not actually exist anywhere in the specimen.
5.2 These test methods may be applied to specimens or products containing randomly intermingled grains of two or more significantly different sizes (henceforth referred to as random duplex grain size). Examples of random duplex grain sizes include: isolated coarse grains in a matrix of much finer grains, extremely wide distributions of grain sizes, and bimodal distributions of grain size.
5.3 These test methods may also be applied to specimens or products containing grains of two or more significantly different sizes, but distributed in topologically varying patterns (henceforth referred to as topological duplex grain sizes). Examples of topological duplex grain sizes include: systematic variation of grain size across the section of a product, necklace structures, banded structures, and germinative grain growth in selected areas of critical strain.
5.4 These test methods may be applied to specimens or products regardless of their state of recrystallization.
5.5 Because these test methods describe deviations from a single, log-normal distribution of grain sizes, and characterize patterns of variation in grain size, the total specimen cross-section must be evaluated.
5.6 These test methods are limited to duplex grain sizes as identifiable within a single polished and etched metallurgical specimen. If duplex grain size is suspected in a product too ...
SCOPE
1.1 These test methods provide simple guidelines for deciding whether a duplex grain size exists. The test methods separate duplex grain sizes into one of two distinct classes, then into specific types within those classes, and provide systems for grain size characterization of each type.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1181 − 02 (Reapproved 2023)
Standard Test Methods for
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Characterizing Duplex Grain Sizes
This standard is issued under the fixed designation E1181; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Test methods are well established for the determination of average grain size, and estimation of
largest grain size, in products assumed to contain a single log-normal distribution of grain sizes. The
test methods in this standard are set forth to characterize grain size in products with any other
distributions of grain size.
The term “duplex grain size” is chosen to describe any of these other distributions of grain size,
because of its common usage and familiarity. However, the use of that term does not imply that only
two grain size distributions exist.
These test methods are equally aimed at describing the nature of the deviation from a single
log-normal distribution of grain sizes, and at describing with reasonable accuracy the distributions of
sizes that actually exist.
1. Scope 2. Referenced Documents
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2.1 ASTM Standards:
1.1 These test methods provide simple guidelines for decid-
E3 Guide for Preparation of Metallographic Specimens
ing whether a duplex grain size exists. The test methods
E7 Terminology Relating to Metallography
separate duplex grain sizes into one of two distinct classes,
E112 Test Methods for Determining Average Grain Size
then into specific types within those classes, and provide
E407 Practice for Microetching Metals and Alloys
systems for grain size characterization of each type.
E562 Test Method for Determining Volume Fraction by
1.2 Units—The values stated in SI units are to be regarded
Systematic Manual Point Count
as standard. No other units of measurement are included in this
E883 Guide for Reflected–Light Photomicrography
standard.
E930 Test Methods for Estimating the Largest Grain Ob-
served in a Metallographic Section (ALA Grain Size)
1.3 This standard may involve hazardous materials,
2.2 ASTM Adjuncts:
operations, and equipment. This standard does not purport to
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Comparison Chart for Estimation of Area Fractions
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to
3. Terminology
establish appropriate safety, health, and environmental prac-
3.1 Definitions:
tices and determine the applicability of regulatory limitations
3.1.1 All terms used in these test methods are either defined
prior to use.
in Terminology E7, or are discussed in 3.2.
1.4 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 bands or banding— in grain size, alternating areas of
ization established in the Decision on Principles for the
significantly different grain sizes. These areas are usually
Development of International Standards, Guides and Recom-
elongated in a direction parallel to the direction of working.
mendations issued by the World Trade Organization Technical
3.2.2 grain size—equivalent in meaning to the average of a
Barriers to Trade (TBT) Committee.
distribution of grain sizes.
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These test methods are under the jurisdiction of ASTM Committee E04 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Metallography and are the direct responsibility of Subcommittee E04.08 on Grain contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Size. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2023. Published May 2023. Originally the ASTM website.
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approved in 1987. Last previous edition approved in 2015 as E1181–02(2015). DOI: This comparison chart shows different area percentages of light grains among
10.1520/E1181-02R23. dark grains. Available from ASTM Headquarters. Order Adjunct: ADJE1181.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E1181 − 02 (2023)
3.2.3 necklace or necklace structure—individual coarse 5. Significance and Use
grains surrounded by rings of significantly finer grains.
5.1 Duplex grain size may occur in some metals and alloys
3.2.4 topologically varying—varying nonrandomly, in some
as a result of their thermomechanical processing history. For
definable pattern; that pattern may be
...
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